Vinyl esters (VE) are useful in the production of paints and as comonomers used to form adhesives. It is well known to form vinyl esters by reacting a carboxylic acid with acetylene according to the following reaction: For example, this reaction is described in U.S. Pat. No. 1,786,647 to Dykstra et al. As a by-product, the reaction also produces an anhydride component primarily in accordance with the following reaction: 
One particularly useful class of vinyl esters are esters of neo acids. In neo acids, the carboxylic acid group is attached to a hydrocarbon backbone through a tertiary carbon atom (a carbon atom that, is attached to three carbon atoms in addition to the carboxylic acid group). Such neo acids, described for example, in U.S. Pat. No. 3,527,779 to Paulis et al., are formed from olefin, carbon dioxide and water via Koch synthesis, and have the general formula: wherein R represents hydrocarbon groups.
The reaction of carboxylic acid and acetylene to form a corresponding vinyl ester is commonly performed in the presence of a zinc carboxylate catalyst. Such catalysts are formed by dissolving zinc oxide, zinc hydroxide or zinc carbonate in a carboxylic acid. (See U.S. Pat. No. 2,066,075 to Reppe). Over the years, a number of improvements to the basic reaction have been proposed. U.S. Pat. No. 3,285,941 to Engel et al. teaches that vinyl esters of carboxylic acids of C8 to C19 alkanes can be formed by passing a gaseous mixture of a vaporized higher carboxylic acids and acetylene into a heated, high boiling, inert liquid containing a dispersed catalyst, controlling conditions such that the concentration of carboxylic acid in the liquid phase is maintained below 5 wt. %, and subsequently separating the vinyl ester from the gaseous effluent of the liquid phase.
U.S. Pat. No. 3,455,998 suggests that the reaction of carboxylic acid and acetylene to form vinyl ester can be conducted more efficiently in the presence of both a zinc carboxylate catalyst and a metal-containing Lewis acid. A still further improvement to the conventional reaction is disclosed in U.S. Pat. No. 3,607,915 to Borsboom et al. which describes a continuous process for producing vinyl esters from carboxylic acid and acetylene, with improved efficiency, by contacting a catalyst-containing reaction recycle stream with at least a portion of the carboxylic acid to be vinylated, before the introduction of the carboxylic acid into the reaction zone of the reactor.
Because of increased demand and fierce competition between manufacturers, there has been a continued need for further improvements that allow for more efficient and lower cost production of vinyl esters from carboxylic acids. The present inventors have developed a novel process involving water treatment of the solution of catalyst, reactants, products and by-products that leads to a more rapid reaction and further lowers costs by converting reaction by-product back into a usable reactant component.
Other and further objects, advantages and features of the present invention will be understood by reference to the following specification.